1. Field of the Invention
The invention relates to plant husbandry and more particularly to plant receptacles.
2. Description of the Prior Art
Sand molded flowerpots have been proposed in the past. Such flowerpots are typically pervious to both air and water, are light weight, have rough interior or exterior surfaces, and are relatively expensive to manufacture due to long molding cycles.
One prior art proposal is disclosed in U.S. Pat. No. 2,810,989. According to the process disclosed in that patent, the shell molding material is either a dry, mechanical mixture of sand and 4 to 15% by weight resin or a sand coated with 2 to 6% resin dissolved in a solvent. An excess of the material is blown or dumped into or on a heated metal pattern and allowed to partially cure, whereupon the pattern is inverted to release excess, uncured material. The sand employed in the process is of medium fineness, i.e. about 75 on the AFS scale, and the molding and curing time is described as ranging from 5 to 15 minutes. The flowerpot produced by the described method has a density of about 60 lbs. per cu. ft. compared to a density of about 100 lbs. per cu. ft. for conventional clay pots.
The resulting flowerpot is pervious to water unless special additives are included in the mix. This characteristic is believed to be due to the fact that the sand has a polarity attraction to water and is therefor easily wetted. The process of using either a mechanical resin-sand mixture or a solvent coating technique is such that the resin melts or coats the sand particles only where they touch each other, while the remaining surface portions are primarily uncoated and exposed. When water is introduced into the prior art pot, it fills the interstices of the wall by capillary action with the result that the pot leaks. Eventually the interstices of the bonded sand structure become filled with salts so that the pot loses its desired breathability or permeability to air.
In order to make the pots of U.S. Pat. No. 2,810,989 impervious to water, it is disclosed that it is necessary to mix fine materials, such as silica flour or zirconite flour, with the medium sand, thereby adding to the cost of manufacture. The use of such additives has the undesirable effect of adversely effecting the permeability of the pot to air.
The flowerpot of U.S. Pat. No. 2,810,989 is further characterized in that the surface which contacts the pattern is smooth, while the opposite surface is rough. The rough surface is undesirable because the pots can be damaged when they are nested for shipment and storage. A rough inner surface has the further disadvantage of making it difficult to transplant.